Severe external and internal bleedings are common in multiple trauma patients. Uncontrollable blood loss is the cause for about one third of all trauma deaths. A number of blood clotting mechanisms are known to be triggered by major blood losses. These mechanisms shall secure the organisms from loosing even more blood. To avoid an overshooting clotting behavior, inhibiting mechanisms occur as well. An important inhibiting (or fibrinolytic) mechanism is the fibrinolysis that is based on the conversion of plasminogen to plasmin. In severe bleeding situations this mechanism tends to overshoot and therewith contributes to the severity of the bleeding. This phenomena is called hyperfibrinolysis and is found in approximately one third of all multiple trauma patients. Mortality rates are increased in these patients. Tranexamic acid is an antifibrinolytic drug that inhibits the conversion from plasminogen to plasmin and therefore is able to limit the effects hyperfibrinolysis. A large study showed positive influence of tranexamic acid on mortality rates and blood loss in severely injured patients, when it was administered in an early clinical setting. In this study we want to answer the question wether a hyperfibrinolysis can be seen in an early prehospital (on the scene) setting and how it is influenced by an early prehospital administration of tranexamic acid.